Apple CEO Tim Cook gave his employees a pat on the back for their contributions to the latest quarterly results.

In an e-mail distributed throughout Apple, Cook praised workers for their "incredible hard work and focus" in "another record setting quarter." Apple's CEO noted that more than 75 million iOS devices were sold last quarter, which he called a "testament to the strength of Apple's innovation."

Team, We've just reported another record setting quarter, thanks to everyone's incredible hard work and focus. We sold over 75 million iOS devices in the holiday quarter alone, which is a testament to the strength of Apple's innovation.

Though Cook seemed pleased with the latest results, at least publicly, Apple investors have been less than kind. The company on Wednesday posted record sales of $54.5 billion, but Wall Street was looking for $54.7 billion. In reaction, Apple's stock has been hammered since the results were revealed on Wednesday.

But much of the concern is over Apple's future. Analysts and investors alike are worried that Apple won't be able to maintain its usual high-growth performance and that its best days may be behind it.